1. Field of the Invention
The invention relates to a vehicular control apparatus that calculates a state of charge (SOC) of an in-vehicle battery and controls a predetermined operation accompanied by charging or discharging the battery on the basis of the calculated state of charge.
2. Description of Related Art
A technique for improving fuel economy of a vehicle by controlling a predetermined operation accompanied by charging or discharging of an in-vehicle battery has conventionally been known (for example, Japanese Patent Application Publication No. 2011-202645 (JP 2011-202645 A) and Japanese Patent Application Publication No. 6-351166 (JP 6-351166 A)).
JP 2011-202645 A discloses a vehicular engine automatic stop/start method for controlling automatic stop and start of an engine (an idle stop operation accompanied by the discharging of the battery). For example, when the vehicle is stopped, the engine is automatically stopped. In this way, fuel consumption during stop of the vehicle can be suppressed, and fuel economy can thereby be improved.
Meanwhile, JP 6-351166 A discloses a vehicular charging control apparatus for controlling an electric power generating operation by an electric power generator (an alternator) that can charge the battery in accordance with the state of charge of the battery. More specifically, an electric power generation voltage is reduced to be lower than a voltage of the battery when the battery is close to be in a fully charged state, so as to reduce an electric power generation amount. On the other hand, when a capacity of the battery is insufficient, the electric power generation voltage is increased to be higher than the voltage of the battery, so as to increase the electric power generation amount. In this way, while the appropriate state of charge of the battery that corresponds to electric power consumption by an auxiliary machine load is secured, an electric power generation load can be reduced and the fuel economy can be improved.
However, there is still room for improvement of the fuel economy that is realized by the above-described control of the predetermined operation accompanied by the charging or discharging of the in-vehicle battery.
For example, in JP 2011-202645 A, in order to prevent a situation in advance where the engine cannot be restarted after the automatic stop, the automatic stop of the engine is suppressed in the case where the calculated SOC of the battery is lower than a preset minimum state of charge. However, if the SOC of the battery is calculated to be lower than the actual SOC, the automatic stop of the engine is suppressed regardless of a fact that the SOC of the battery is equal to or more than the minimum state of charge. In this case, the fuel economy may not sufficiently be improved. In other words, in the case where accuracy of the calculated SOC of the battery is poor, the fuel economy may not sufficiently be improved by the control of the idle stop operation.
In addition, in JP 6-351166 A, if the SOC of the battery is calculated to be lower than the actual SOC, the electric power generation amount is not reduced regardless of a fact that the battery is actually in a fully charged state. In this case, wasteful electric power generation continues, and the fuel economy may not sufficiently be improved. In other words, in the case where the accuracy of the calculated SOC of the battery is poor, the fuel economy may not sufficiently be improved by the control of the electric power generating operation of the alternator.